Photographic silver halide emulsions and elements



United States Patent 3,516,830 PHOTOGRAPHIC SILVER HALIDE EMULSIONS AND ELEMENTS Thomas E. Whiteley, Rochester, N.Y., assignor to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Filed Sept. 17, 1965, Ser. No. 488,254 Int. Cl. G03c 1/04 U.S. Cl. 96-67 12 Claims ABSTRACT OF THE DISCLOSURE High contrast photographic silver halide emulsions having a binding agent of aqueous silver halide peptizer and a water-insoluble polymeric vinyl compound and containing a water-soluble block copolymer comprising blocks of polyoxyethylene and polyoxypropylene are disclosed. In photographic elements containing such emulsions, the water-soluble block copolymer can be in a layer other than the emulsion layer.

This invention relates to photographic materials, their preparation and use. In one of its aspects, this invention relates to photographic silver halide emulsion layers. In another of its aspects, this invention relates to photographic elements bearing photographic silver halide layers and the use of such elements in photolithography.

Photographic silver halide elements, particularly those used in the graphic arts industry for the production of lithographic plates, must have good physical and photographic properties. In U.S. Pat. 3,142,568, issued July 28, 1964, it is shown that a number of properties, including dot quality, contrast and dimensional stability of a photographic silver halide layer can be improved if the binding agent employed in the emulsion layer comprises a mixture of gelatin and a vinyl polymer and the layer contains an amphoteric dispersing agent and a polyethylene glycol or ether thereof. However, the presence of a dispersing agent in such photographic emulsion layers often adversely affects both the hardness of the layers and the photographic quality of lithographic plates prepared from prints containing such emulsion layers. Furthermore, it is often necessary to employ rather high concentrations, for example, concentrations in excess of one gram per mole of silver halide of polyethylene glycol or ethers thereof in the aforementioned photographic emulsion layers in order to achieve the desired photographic properties. Such high cencentrations of polyethylene glycol or ethers thereof can result in excessively high fog, particularly at prolonged development times, and when the element is processed in a lithographic developer solution having a relatively high concentration of sulfite which is added to improve stability. In addition, polyethylene glycol or ethers thereof tend to difiuse out of a photographic emulsion layer during development which gives rise to problems in processing.

Accordingly, it is an object of this invention to provide a photographic silver halide emulsion layer which exhibits excellent physical and photographic properties.

Another object of this invention is to provide a photographic element in which there is incorporated at least one such photographic silver halide emulsion layer.

Another object of this invention is to provide a photographic element and a photographic silver halide emulsion layer containing a novel combination of ingredients.

Another object of this invention is to provide a photographic silver halide emulsion layer which does not require the presence of an amphoteric dispersing agent to exhibit good physical and photographic properties.

Still another object of this invention is to provide a "ice method for obtaining a lithographic film or plate which is superior in quality to a film or plate containing polyethylene glycol or ethers thereof, in a photographic silver halide emulsion layer.

Other objects of this invention will become apparent from an examination of the specification and claims which follow.

In accordance with this invention, it has been found that the above and other objects can be attained by providing a photographic silver halide emulsion wherein the binding agent comprises an aqueous silver halide peptizer and an aqueous dispersion of about 20 to about 80%, by weight, of a polymeric compound and said emulsion contains a water-soluble block copolymer comprising blocks of polyoxyethylene and polyoxypropylene, all as described hereinafter.

A significant feature of this invention is the fact that the binding agent for the photographic silver halide emulsion layer must be an aqueous mixture of dispersed polymeric vinyl compound and silver halide peptizer, preferably a protein such as gelatin, in order to achieve the desired combination of physical and photographic properties. For example, the omission of the vinyl polymer from the binding agent significantly reduces dot quality and dimensional stability. On the other hand, the vinyl polymer does not exhibit the very good peptizing action of such colloids as gelatin for silver halide and this action is needed in the preparation of the photographic silver halide emulsions. Furthermore, the use of the block copolymers described herein, rather than polyethylene glycol or ethers thereof, in the photographic silver halide emulsions of this invention overcomes several of the disadvantages associated with the use of the latter.

One component of the binding agent for the photographic silver halide emulsions described herein is an aqueous dispersion of polymeric vinyl compound. The preferred polymeric vinyl compounds are homo or copolymers prepared from acrylic acid and esters thereof. These polymers are insoluble in water and can be readily dispersed in water and mixed With a suitable silver halide peptizer such as gelatin. The vinyl polymers are generally employed in concentrations in the range of about 20 to 80%, most often concentrations at least by Weight, based on the weight of the binding agent. The remainder of the binding agent is a silver halide peptizer such as gelatin, alone or with another photographic binding material. Good results are achieved with polymers of alkyl acrylates or methacrylates which are obtained by homopolymerizing these monomers or interpolymerizing these monomers with each other or with different ethylenically unsaturated polymerizable compounds, containing one or more groups, or more particularly one or more CH2=C groups, to form water-insoluble addition polymers. In general, it is desirable to employ a polymeric vinyl compound Which contains, in polymerized form, at least preferably about to about by Weight, of an alkyl acrylate or methacrylate, as exemplified by ethyl acrylate, methyl acrylate, butyl acrylate, ethyl methacrylate, octyl methacrylate, and the like. Suitable ethylenically unsaturated comonomers which can be interpolymerized With these materials to form Water-insoluble addition polymers include, for example, vinyl esters, amides, nitriles, ketones, halides, ethers, o e-unsaturated acids or esters thereof, olefins, diolefins and the like, as exemplified by acrylonitrile, methacrylonitrile, styrene, a-methylstyrene, vinyl chloride, vinylidene chloride, methyl vinyl ketone, vinyl acetate, fumaric, maleic and itaconic acid esters, 2 chloroethylvinylether, methylenemaleonitrile, acrylic acid, methacrylic acid, dirnethylaminoethylmethacrylate, N vinylsuccinimide, N vinylphthalimide, N- vinylpyrrolidone, butadiene, isoprene, vinylidene cyanide and the like. The polymeric vinyl compounds most useful in the practice of this invention generally have an average molecular weight in the range of about 5000 to about 500,000 and a particle size in the dispersion which is generally less than 1 micron.

A preferred class of vinyl polymers which can be employed in the practice of this invention are water-insoluble interpolymers of acrylates or methacrylates with acrylic acid and a sulfobetaine having the formula:

where R, R and R are each hydrogen or alkyl and R and R are each divalent saturated hydrocarbon radicals, desirably containing up to 12 carbon atoms. Suitable sulfobetaine monomers include, for example, 5,5,10-trimethyl 9 oxo-8-oxa-5-azonia-IO-undecene-l-sulfonate, 4 t-butyl-9-methyl-8oxo-7-oxa-4-aza-9-decene-l-sulfonic acid, 4,4,9 trimethyl 8-oxo-7-oxa-4-azonia-9-decene-lsulfonate, and the like. The preferred polymers of this type contain, in polymerized form, at least 75%, preferably about 75 to about 93%, by weight, of acrylate or methacrylate, up to about 15%, preferably about 5 to about 15 by weight, acrylic acid and up to about 10%, preferably about 2 to about 10%, by weight, of the sulfobetaine.

A very convenient method for preparing the sulfobetaine monomers used in preparing the aforementioned preferred class of polymeric vinyl compounds comprises reacting the appropriate amino alkyl ester of an unsaturated carboxylic acid with the appropriate sultone. Such a reaction can be carried out in the presence of an organic solvent such as acetonitrile, a liquid hydrocarbon or a ketone such as acetone at temperatures up to about 100 C., preferably 50 to about 80 C. In general, the reaction is complete in less than 8 hours, often in about 2 to about 6 hours. The reaction is not pressure dependent and therefore superatmospheric or subatmospheric pressures can be employed. The resulting sulfobetaine can be isolated by conventional procedures. The reactants are generally employed in stoichiometric concentrations although slight excesses of either reactant can be employed. As is obvious to one skilled in the art the specific reaction conditions, for example, temperature, pressure, and the like, will depend upon the particular amino alkyl ester and sultone employed. Another suitable method for preparing the sulfobetaines, particularly where R and R in the above formula are both hydrogen, is to react the appropriate hydroxyalkyl amine with the required sultone and then esterify with acrylic acid or with a derivative thereof.

Another class of polymeric vinyl compounds which is preferred in the practice of this invention is the interpolymers of alkyl acrylates or methacrylates with sulfoesters having the formula:

where R is hydrogen or alkyl, R has its valence bonds on different carbon atoms and is a divalent hydrocarbon radical or aliphatic divalent hydrocarbon radical in which a carbon chain joining the oxygen and sulfur atoms in the formula shown is interrupted by at least one oxygen and/or sulfur radical and M is a cation. Suitable R groups include hydrogen or any of the alkyl radicals, preferably alkyl radicals containing up to about 12 carbon atoms, often 1-8 carbon atoms, as exemplified by methyl, ethyl, propyl, pentyl, octyl, dodecyl and the like. R has its valence bonds on different carbon atoms and can be a hydrocarbon radical or it can be an aliphatic hydrocarbon radical in which a chain of carbon atoms joining the oxygen and sulfur atoms in the formula shown above is interrupted by an atom from Group VI-A of the Periodic Table having an atomic Weight less than about 33, i.e., at least one O and/or S- radical interrupts the carbon chain. Where R is hydrocarbon, it can be any aliphatic, cycloaliphatic or aromatic radical and will generally contain up to about 12 carbon atoms. Preferred hydrocarbon R radicals are alkylene radicals, generally those containing 2-4 carbons. R can also be a divalent aliphatic hydrocarbon radical in which there is a O- and/or S radical and generally contains up to 12 carbon atoms. Such R radicals can, therefore, be saturated or unsaturated, although saturated divalent alkylene groups in which the carbon chain is interrupted by oxygen and sulfur atoms are preferred. Suitable R radicals include, for example, ethylene, 1,3-propylene, 1,2-propylene, tetramethylene, 1,3-isobutylene, pentamethylene, hexamethylene, octamethylene, phenylene, bisphenylylene, naphthylene, cyclopentylene, cyclohexylene, Z-butenylene, butynylene, 2-oxatrimethylene, 3-thiapentamethylene, and the like. M is a cation, as exemplified by hydrogen, an alkali metal such as sodium or potassium, ammonium, the cation of an organic amine such as triethyl amine, diethanol amine and the like.

The sulfoesters can be prepared using any method known to be suitable for this purpose. For example US. Pat. 2,923,734, issued Feb. 2, 1960, discloses the preparation of such esters by the reaction of an a-methylene carboxylic acid with an aliphatic hydroxy sulfonic acid while US. Pat. 3,024,221, issued Mar. 6, 1962, discloses a method for preparing the sulfoester by reacting the appropriate acyl halide with the salt of the hydroxy sulfonic acid. Examples of hydroxy sulfonic acids (and their salts) that can be employed to form the sulfoesters are 2-hydroxyethane sulflonic acid, 2-hydroxy-l-propane sulfonic acid, 1-hydroxy-2-butane sulfonic acid, Z-hydroxycyclohexane sulfonic acid, p-phenolsulfonic acid, 2-(2-hydroxyethoxy)ethane-1-sulfonic acid, 2-(2-hydroxyethylthio) ethane-l-sulfonic acid, 4-hydroxy-2-butene-l-sulfonic acid, 4-hydroxy-2-butyne-l-sulfonic acid and the like. a-Methylene carboxylic acids or acyl halides includes acrylic acid, methacrylic acid, a-butylacrylic acid, acryloyl chloride, methacryloyl bromide, m-hexylacryloyl chloride and the like. The preferred class of polymers of the sulfoesters generally contains, in polymeric form, at least 65%, preferably about to about by weight, of the alkyl acrylate or methacrylate and up to about 15%, preferably about 5 to about 15%, by weight, of the sulfoester.

The temperature at which the polymeric vinyl compounds employed in the practice of this invention are prepared is subject to wide variation since this temperature depends upon such variable features as the specific monomer used, duration of heating, pressure employed and like considerations. However, the polymerization temperature generally does not exceed about C., and most often, is in the range of about 50 to about 90 C. The polymerization can be carried out in suitable solvents or diluents, for example, water or mixtures of water with water miscible solvents, as exemplified by methanol, ethanol, propanol, isopropyl alcohol, butyl alcohol, and the like. The pressure employed in the polymerization, if any,

is usually only sufficient to maintain the reaction mixture in liquid form, although either superatmospheric or subatmospheric pressures can be used. The concentration of polymerizable monomer in the polymerization mixture can be varied widely with concentrations up to about 40 percent, by weight, and preferably about 20 to about 40 percent, by weight, based on the weight of the vehicle being satisfactory. Suitable catalysts for the polymerization reaction include, for example, the free radical catalysts, such as hydrogen peroxide, cumene hydroperoxide, water soluble azo type initiators and the like. In redox polymerization systems the usual ingredients can be employed. If desired, the polymer can be isolated from the reaction vehicle by freezing, salting out, coagulation or by using other separation procedures suitable for this purpose.

The photographic silver halide can be dispersed in the binding agent in a variety of ways, for example, an aqueous dispersion of the photographic silver halide in peptizer can be mixed with an aqueous dispersion of the polymeric vinyl compound. Alternatively, the photographic silver halide can be precipitated in an aqueous dispersion of the polymeric vinyl compound and peptizing agent such as gelatin. In this case, a water soluble silver salt such as silver nitrate is admixed with the silver halide such as potassium bromide in the presence of the mixture. In still another procedure, the photographic sil ver halide is precipitated in an aqueous gelatin solution and digested in the conventional manner known to the art. After digestion, but prior to coating, there is added to the emulsion an aqueous dispersion of the polymeric vinyl compound. The bulk of the resulting dispersion can be increased by the addition of more of the polymeric vinyl compound and/or natural or synthetic colloids or other binding materials suitable for use in photographic silver halide emulsions.

Unlike the polyethylene glycol or ethers thereof, the water-soluble block copolymers employed in the practice of this invention contain polyoxypropylene blocks. The polyoxypropylene moiety in the block copolymer has an average molecular weight in the range of about 800 to about 3,000 and the polyoxyethylene moiety which is also present constitutes about to about 70%, by weight, of the block copolymer. The water-soluble block copolymers which can be employed in the practice of this invention include those represented by the Formula I:

wherein Y is an organic radical having a valence of x, said radical being the residue of an organic compound, e.g., one containing atoms such as carbon, hydrogen, oxygen, nitrogen and/or sulfur with x active hydrogen atoms as exemplified by the residue of polyhydroxy compounds such as ethylene glycol, l,2-propanediol, 1,5-pentanediol, 1,2,3-propanetriol, sucrose, etc., the residue of a polybasic acid such as oxalic acid, malonic acid, succinic acid, maleic acid, citric acid, etc., the residue of a polyamine such as ethylene diamine, 1,3-diaminopropylene, etc., the residue of a polyamide, such as malonamide, succinamide, etc., the residue of a polythiol, such as 1,2-ethylenedithiol, 1,3-propylenedithiol, etc., n is an integer greater than 1, x is an integer greater than 1, the values of n and x being such that the molecular weight of said copolymer, exclusive of Y, E and R, is in the range of about 800 to about 3,000, B is a polyoxyethylene chain constituting about 10 to about 70 percent, by weight, of said block copolymer and R is a hydrogen atom, an alkyl group desirably having from 1 to carbon atoms (such as methyl, propyl, decyl, dodecyl, octadecyl, etc.), an alkyl carbonyl group, desirably one in which the alkyl group has from 1 to 20 carbon atoms as described above or an aryl carbonyl group, such as, benzoyl, p-methyl benzoyl, etc.

Included among the preferred block copolymers are those having the Formula H:

HO (CHzCHzO) B[OHCH20] (CHzCHzOhH in which b is an integer in the range of about 14 to about 52, a and c are each integers such that the sum of a-i-c is an integer in the range of about 4 to about 48 and the 75 polyoxyethylene groups constitute between 10 and percent, by weight, of the block copolymer.

The block copolymers of Formulae I and II where R represents the hydrogen atom are described in Lundsted US. Pat. 2,674,619, issued Apr. 6, 1954 and Lundsted US. Pat. 3,022,335, issued Feb. 20, 1962. The block copolymers of Formula I in which R is hydrogen are readily converted to compounds where R represents an organic residue by reaction with the appropriate reagent in a suitable inert organic solvent that is preferabbly anhydrous. For example, alkyl halides, such as alkyl chlorides and alkyl bromides, are used to advantage to replace the terminal hydrogen atom of the block copolymer with an alkyl group. Alkyl-p-toluenesulfonates are also used to advantage to place an alkyl group on the end of the block copolymers. The appropriate acid chloride or acid anhydride such as acetyl chloride, propionyl chloride, stearoyl chloride, benzoyl chloride, acetic anhydride, etc., are used to advantage to prepare block copolymers of Formula I in which R is an alkyl carbonyl or an aryl carbonyl group. These reactions are well known to those skilled in the art.

' groups terminated by hydrogen and hydroxy groups as shown in Formula II. However, another class of block copolymers which gives very good results are the block copolymers in which the main chain contains other atoms, particularly silicon atoms, with the polyoxyethylene and polyoxypropylene groups. Such block copolymers generally contain only minor amounts, for example, up to about 15%, generally about 2 to about 15%, by weight, of atoms such as silicon in the body of the chain and/ or in the terminating positions. To obtain the desired photographic results, the oxyalkylene groups within the block copolymer should maintain the average molecular weight and concentration relationship described hereinabove. Block copolymers containing silicon can be obtained by reacting the block copolymer of Formula I in which R is hydrogen with a siloxane monomer or polymer such as the dimer. Block copolymers containing oxyalkylene groups bonded to siloxane groups are described in US. Pat. 2,917,480, issued Dec. 15, 1959.

The block copolymers employed in the practice of this invention are water soluble and are advantageously added in a water solution to aqueous hydrophilic colloid, either with or without the silver halide, before coating the emulsion layer. The block copolymers are generally employed in concentrations in the range of about .001 to about 1 gram of block copolymer per mole of silver halide, the preferred concentration being in the range of about .01 to about .2 gram per mole of silver halide. In practicing this invention the water soluble block copolymers are incorporated into at least one layer of the photographic element and are contiguous to or in close proximity to the photographic silver halide. For example, these block copolymers can be incorporated into the photographic silver halide emulsion layer, or an adjacent or effectively adjacent layer of the photographic element.

Typical block copolymers that can be employed in the practice of this invention include the following:

TABLE I Percent polyoxyethylene Block Average value by weight Polymer Y Group derived of n in of block o. from- Formula I copolymer 1 1,2propauediol 30 10 2 do 30 20 22 40 30 50 30 40 56 20 39 10 24 50 9 1,2,3-propanetriol 36 48 10 Ethylenediamine In addition, typical block copolymers which contain silicon are obtained by reacting a dimethyl siloxane monomer or dimer with block polymer No. 3 to introduce 5 to about 9%, by weight, of silicon into the main polymer chain.

The photographic silver halide emulsions employed in the practice of this invention are lithographic silver halide emulsions in which the halide generally comprises at least 50 mole percent chloride. Such high contrast emulsions preferably contain at least 60 mole percent chloride, less than 40 mole percent bromide and less than 5 mole percent iodide. Suitable silver halides include, for example, silver chloride, silver chlorobromide, silver chlorobromoiodide and the like.

The aqueous silver halide peptizing agent which constitutes one component of the binding agent for the photographic silver halide emulsion described herein is preferably gelatin. However, other hydrophilic colloids can be employed in place of or in combination with gelatin. Furthermore, the binding agent can also comprise other binding materials, for example, synthetic polymers which are not silver halide peptizers, so long as some aqueous silver halide peptizer is present to give the required peptization. In the preferred case, the binding agent comprises a mix ture of polymeric vinyl compound, in a concentration in the range of about to about 80 percent, by weight, with the remainder of the binding agent being gelatin. Typical hydrophilic colloids that can be used in the binding agent include for example, gelatin, colloidal albumin, cellulose derivatives and the like.

The photographic compositions described herein can be coated on a wide variety of supports. Typical supports are the flexible supports of materials such as aluminum, paper, cellulose acetate film, polyvinyl acetal film, polystyrene film, polyolefin film, polycarbonate film, polyethylene terephthalate or other polyester film and other related materials. Supports such as paper which are partially acetylated or coated with an OL-OlCfiIl polymer, particularly a polymer of an a-olefin containing 2-10 carbon atoms, as exemplified by polyethylene, polypropylene, ethylene butene copolymers and the like, give good results.

The photographic silver halide emulsions described herein can be chemically sensitized with compounds of the sulfur group or noble metal salts such as gold salts, reduction sensitized with reducing agents and combinations of these. Furthermore, photographic silver halide emulsion layers and other layers present in the photographic elements made according to the invention can be hardened with any suitable hardeners such as aldehyde hardeners, aziridine hardeners, hardeners which are derivatives of dioxane, oxy polysaccharides, such as oxy starch, oxy plant gums and the like. The photographic emulsions can also contain additional additives, particularly those known to be beneficial in photographic emulsions, including for example, stabilizers or antifoggants, particularly the water soluble inorganic acid salts of cadmium, cobalt, manganese and zinc such as disclosed in U.S. Pat. 2,829,- 404, the substituted triazaindolizines as disclosed in U.S. Pats. 2,444,605 and 2,444,607, spectral sensitizers such as the cyanines, merocyanines, complex(trinuclear) cyanines, complex(trinuclear) merocyanines, styryls, hemicyanines, speed increasing materials, plasticizers and the like. If desired, coating aids can also be used in the photographic emulsions. Typical coating aids are the anionic, non-ionic and amphoteric surface active compounds.

It is particularly advantageous to add certain onium salts such as quaternary ammonium salts, sulfonium salts and phosphonium salts to the light-sensitive emulsions disclosed herein to increase photographic speed without ad versely affecting dot quality, contrast and evenness of development. Examples of the quaternary ammonium salts include nonyl pyridinium perchlorate, hexoxymethyl pyridinium perchlorate, ethylene bisdioxymethyl pyridinium perchlorate and others described by Caroll US. 2,271,623, issued Feb. 3, 1942, hexadecamethylene-1,l6- bis (pyridinium perchlorate), 9,16-diaza-7,18-dioxa-8,l7- dioxotetracosane-1,24-bis(pyridinium perchlorate), and others of Beavers et al. U.S. 2,944,898, issued July 12, 1960. Other examples include onium salts of polyoxyalkylenes of Carroll et al. U.S. 2,944,902, issued July 12, 1960, the polyonium salts of Carroll et al. U.S. 2,288,226, issued June 30, 1942, such as bis(lturyl methyl sulfonium p-toluene sulfonate) 1,2-ethane, N,N-trimethylene dioxymethyl pyridinium perchlorate, etc., the sulfonium salts of Carroll et al. U.S. 2,275,727, issued Mar. 10, 1942, such as n-decyl dimethyl sulfonium p-toluene sulfonate, and n-nonyl dimethyl sulfonium p-toluene sulfonate, etc., and the phosphonium salts of Carroll et al. U .8. 2,271,622, issued Feb. 3, 1942 such as tetramethylene bis-triethyl phosphonium bromide, lauryl-triethylphosphonium bromide, etc.

The quality of the silver images produced in the practice of this invention is conveniently measured in terms of contrast (i.e., 'y) and dot quality photographic image contrast is the slope of the straight line portion of a graph of optical density of the image vs. log of exposure. Dot quality is a measure of the quality of the reproduction of a half-tone image. Photographic elements of the Lith Type, as described herein, when exposed to a half-tone image, and developed, produce areas commonly referred to as shadow dots and areas known as highlight areas. Intermediate between these two extremes are areas of varying size. The dot quality used herein is a measure of the areas referred to as 50% dots (i.e., /2 clear, and /2 developed density) and is expressed in a progressive scale where 9 is excellent and 1 is extremely poor. A 50% dot quality below 6 is generally not acceptable. Photographic speed, as reported hereinafter, is indicated as a function of the exposure necessary to give a density of .6 above background fog, the initial control speed being taken as 100 in each case.

This invention can be further illustrated by the following examples of preferred embodiments thereof although it will be understood that these examples are included merely for purposes of illustration and are not intended to limit the scope of the invention unless otherwise specifically indicated.

EXAMPLE 1 Photographic elements containing the alkylene oxide block copolymers described herein exhibit improved properties in comparison to elements containing polyethylene glycol or ethers thereof. To illustrate, four runs are made as follows:

Run 1 Run 2 A coating is prepared in the same manner as in Run 1 except that the aqueous binding agent comprises 40 grams of gelatin and grams of a copolymer of butyl acrylate with acrylic acid (:10, by weight).

Run 3 A coating is prepared as in Run 2 except that the concentration of oleyl ether of polyethylene glycol is increased to 1.12 grams per mole of silver.

Run 4 A coating is prepared as in Run 1, except that the polyethylene glycol is replaced by 0.035 gram per mole silver of block polymer No. 3 of Table I, i.e., a block copolymer having a molecular Weight of 2,000 wherein the polyoxypropylene moiety has a molecular weight of 1,200 and the percent, by Weight, of polyoxyethylene in the copolymer is 40%.

A sample of each coating is given an identical exposure to a white light tungsten source through an intensity scale sensitometric step wedge and subsequently developed for 2% minutes at a temperature of 68 F. in the following lithographic developer solution (Developer A):

Hydroquinone 15.0 Sodium formaldehyde bisulfite 50.0 Sodium carbonate 35.0 Sodium bicarbonate 22.5 Sodium sulfite 2.5 Potassium bromide 0.75

Water to 1 liter.

Each sample is fixed, washed and dried in the conventional manner and the following sensitometric data ob- It can be seen from the above table that the oleyl ether of polyethylene glycol gives a dot quality in the vinyl polymer containing coatings which is very similar to that of the all gelatin coating only with a significant reduction in speed. Furthermore, it can be seen that much smaller concentrations of the block copolymers of this invention give good dot quality and contrast without any significant reduction in speed. In addition, each of the coatings containing the dispersed polymeric vinyl compound exhibits greatly improved dimensional stability in comparison to the coating (Run 1) using a binding agent which is all gelatin. Also, omitting the polymeric vinyl compound from. the coating in Run 4 reduces dot quality by more than Results similar to those reported above are obtained with a block copolymer containing polyethyleneoxy, polypropyleneoxy and polydimethyl siloxane units in which the polyethyleneoxy units comprise by weight, of the block copolymer, the polypropyleneoxy moiety has an average molecular weight of 1,200 and the silicon content is approximately 5.7, 6.0 or 6.5 weight percent.

EXAMPLE 2 As illustrated in Example 1, polyethylene glycol or ethers thereof must be used at higher concentrations than the block copolymers disclosed herein to obtain the desired contrast and dot quality. Such high concentrations result in excessive fog upon development, particularly upon development in the more stable lithographic developers containing a high concentration of sulfite. To illustrate, unexposed samples of each of Runs 1-4 of Example 1 are immersed for 4 minutes at 68 F. in the following high sulfite lithographic developer solution (Developer B):

Gm. p-Methylaminophenol 1.0 Sodium sulfite, desiccated 75.0 Hydroquinone 9.0 Sodium carbonate, monohydrated 30.0 Potassium bromide 5.0

Water to make 1.0 liter.

Each sample is fixed, washed and dried in the conventional manner and the following results are obtained Run: Fog l .09 2 .12 3 .26

EXAMPLE 3 A photographic silver halide emulsion is prepared as in Example 1, Run 1, except that the aqueous binding agent comprises 40 grams of gelatin and grams of a copolymer of butyl acrylate, acrylic acid and 4,4,9- trimethyl-8-oxo 7-oxa-4-azonia-9-decene-l-sulfonate dis persed in Water. The emulsion is divided into equal parts and the following addenda is added, per mole of silver halide:

(1) 0.112 gram of oleyl ether of polyethylene glycol (average mol. weight 1540) (2) 1.12 grams of oleyl ether of polyethylene glycol (average mol. weight 1540) (3) 0.035 gram of a polyoxypropylene-polyoxyethylene block copolymer (average mol. weight 2000) containing polyoxypropylene blocks having an average molecular weight of 1,200 and about 40%, by weight, of polyoxyethylene blocks.

Each sample is coated according to Example 1. One sample of each run is exposed as in Example 1 and developed in Developer A While another unexposed sample of each run is tested according to Example 2 using Developer B. After fixing, washing and drying in the conventional manner, the samples are sensitometrically evaluated and the following results obtained:

Developer A Relative Developer 13 speed Contrast Dot quality Fog In this example, as in 'Example 1, no amphoteric surface active agent is employed to disperse the polymeric vinyl compound in the photographic emulsion.

"EXAMPLE 4 As previously indicated, interpolymers of alkyl acrylates or methacrylates with sulfoesters are particularly suitable polymeric vinyl compounds Which can be used in the practice of this invention. To illustrate, the following runs are made.

Run 1 An emulsion is prepared as in Example 1, Run 1, with the incorporation of 0.112 gram of oleyl ether of polyethylene glycol (average molecular weight 1540) per mole of silver halide.

Run 2 An emulsion is prepared as in Example 1, Run 1, except that the binding agent comprises 54 grams of gelatin and 54 grams of a water insoluble copolymer of methylacrylate and sodium acryloyl-l-propane sulfonate per mole of silver halide. 0.112 gram of the oleyl ether of polyethylene glycol per mole of silver halide is added to the emulsion.

Run 3 An emulsion is prepared as in Run 2 of this example but the oleyl ether of polyethylene glycol is replaced by 0.025 gram of a block copolymer containing polyoxyethylene and polyoxypropylene units; the copolymer has an average molecular weight of 2,000, the polyoxypropylene moiety has an average molecular weight of 1,200 and the percent, by weight, of polyoxyethylene in the polymer is 40%.

After processing, as in Example 1, in Developer A, the following results are obtained:

Run Contrast Dot quality Thus, by the practice of this invention there is provided a photographic silver halide emulsion and element which can be employed in the graphic arts industry for the production of lithographic plates having good physical and photographic properties. The use of the particular combination of ingredients described herein provides a lithographic film emulsion which, when coated as a layer on a support, exhibits good dimensional stability, flexibility and the like, as well as improved photographic contrast, half-tone dot quality and development and exposure latitude.

Although the invention has been described in considerable detail with reference to certain preferred embodiinents thereof, it will be understood that variations and modifications can be effected without departing from the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

I claim:

1. A photographic silver halide emulsion in which the halide comprises at least 50 mole percent chloride, said emulsion having a binding agent comprising an aqueous silver halide peptizer and an aqueous dispersion of about 20 to about 80%, by weight, of a water-insoluble polymeric vinyl compound having an average molecular weight in the range of about 5,000 to about 500,000 and a particle size in the dispersion which is generally less than 1 micron and, said emulsion containing a watersoluble block copolymer comprising blocks of polyoxyethylene and polyoxypropylene, about 10 to about 70%, by weight, of said copolymer being polyoxyethylene and the average molecular weight of polyoxypropylene in said copolymer being in the range of about 800 to about 3,000.

2. A photographic silver halide emulsion in which the halide comprises at least 50 mole percent chloride, said emulsion having a binding agent comprising an aqueous silver halide peptizer and an aqueous dispersion of about 20 to about 80%, by weight, of a water-insoluble polymeric vinyl compound having an average molecular weight in the range of about 5,000 to about 500,000 and a particle size in the dispersion which is generally less than 1 micron and, said emulsion containing about .001 to about 1 gram, per mole of silver halide, of a watersoluble block copolymer comprising blocks of polyoxyethylene and polyoxypropylene, about 10 to about 70%, 'by weight, of said copolymer being polyoxyethylene and the average molecular weight of polyoxypropylene in said copolymer being in the range of about 800 to about 3,000.

3. The photographic emulsion of claim 1 in which the block copolymer contains up to about by weight, of silicon atoms in the main polymer chain.

4. A photographic silver halide emulsion in which the halide comprises at least 50 mole percent chloride, said emulsion having a binding agent comprising aqueous gelatin and an aqueous dispersion of about to about 80%, by weight, of a water-insoluble polymeric vinyl compound having an average molecular weight in the range of about 5,000 to about 500,000 and a particle size in the dispersion which is generally less than 1 micron and, said emulsion containing about .001 to about 1 gram per mole of silver halide, of a water-soluble block copolymer comprising blocks of polyoxyethylene and polyoxypropylene, about 10 to about 70%, by Weight, of said copolymer being polyoxyethylene and the average molecular weight of the polyoxypropylene in said copolymer being in the range of about 800 to about 3,000.

5. The photographic silver halide emulsion of claim 4 in which the water-soluble block copolymer has the formula:

where Y is an organic radical having a valence of x; n is an integer, x is an integer greater than 1, the values of n and x being such that the molecular Weight of said copolymer exclusive of Y, E and R is in the range of about 800 to about 3,000; B being a polyoxyethylene chain constituting from about 10 to about 7 0%, by weight, of said copolymer and R is a hydrogen atom, an alkyl group, an alkyl carbonyl group or an aryl carbonyl group.

6. The photographic silver halide emulsion of claim 4 in which the water-soluble block copolymer has the formula:

where b is an integer in the range of about 14 to about 52, a and c are each integers such that the sum of a+c is an integer in the range of about 4 to about 48 and the polyoxyethylene groups constitute about 10 to about 70%, by weight, of said copolymer.

7. The photographic silver halide emulsion of claim 4 in which the polymeric vinyl compound is a copolymer of an alkyl acrylate and a monomer having the formula:

where R is hydrogen or alkyl, R has its valence bonds on different carbon atoms and is a divalent hydrocarbon radical or a divalent aliphatic hydrocarbon radical in which the chain of carbon atoms joining the oxygen and sulfur atoms of the above formula is interrupted by an oxygen and/ or sulfur atom and M is a cation.

8. The photographic silver halide emulsion of claim 4 in which the polymeric vinyl compound is a copolymer of an alkyl acrylate, acrylic acid and a monomer having the formula:

where R, R and R are each hydrogen or alkyl and R and R are each divalent saturated hydrocarbon radicals.

9. A photographic element comprising a support, a photographic silver halide layer in which the halide is at least 50 mole percent chloride, said emulsion layer having a binding agent comprising a silver halide peptizer and about 20 to about by weight, of a water-insoluble polymeric vinyl compound having an average molecular weight in the range of about 5,000 to about 500,000 and a particle size in the dispersion which is generally less than 1 micron, and incorporated in at least one layer of said element and contiguous to or in close proximity to the said photographic silver halide, a water-soluble block copolymer comprising blocks of polyoxyethylene and polyoxypropylene, about 10 to about 70%, by weight, of said copolymer being polyoxyethylene and the average molecular weight of polyoxypropylene in said copolymer being in the range of about 800 to about 3,000.

10. A photographic element comprising a support, a photographic silver halide layer in which the halide comprises at least 50 mole percent chloride, said emulsion layer having a binding agent comprising a silver halide peptizer 1 and about 20 to about 80%, by weight, of a water-insolucopolymer comprising blocks of polyoxyethylene and polyoxypropylene, about to about 70%, by Weight, of said copolymer being polyoxyethylene and the average molecular weight of polyoxypropylene in said copolymer being in the range of about 800 to about 3,000.

11. A photographic element comprising a support, a photographic silver halide layer in which the halide comprises at least 50 mole percent chloride, said emulsion layer having a binding agent comprising gelatin and about 20 to about 80%, by weight, of a Water-insoluble polymeric vinyl compound having an average molecular Weight in the range of about 5,000 to about 500,000 and a particle size in the dispersion which is generally less than 1 micron, and incorporated in at least one layer of said element and contiguous to or in close proximity to the said photographic silver halide, about 0.001 to about 1 gram, per mole of silver halide, of a water-soluble block copolymer comprising blocks of polyoxyethylene and polyoxypropylene having the formula:

where Y is an organic radical having a valence of x; n is an integer; x is an integer greater than 1, the values of n and x being such that the molecular weight of said copolymer exclusive of Y, E and R is in the range of about 800 to about 3,000; E being a polyoxyethylene chain constituting from about 10 to about 70%, by weight, of said copolymer and R is a hydrogen atom, an alkyl group, an alkyl carbonyl group or an aryl carbonyl group.

12. A photographic silver halide emulsion in which the halide comprises at least 50 mole percent chloride, said emulsion having a binding agent comprising gelatin and an aqueous dispersion of about 20 to about 80 percent by weight of a water-insoluble copolymer of an alkyl acrylate and a monomer having the formula:

Where R is hydrogen or alkyl, R has its valence bonds on diiferent carbon atoms and is a divalent hydrocarbon radical or a divalent aliphatic hydrocarbon radical in which the chain of carbon atoms joining the oxygen and sulfur atoms of the above formula is interrupted by at least one oxygen and/or sulfur radical and M is sodium, said emulsion containing about .001 to about 1 gram per mole of silver halide of a water-soluble block copolymer having the formula:

HO(GH2CHZO)Q CHCHzO (GHzCHzOhH where b is an integer in the range of about 14 to about 52, a and c are each integers such that the sum of a-l-c is an integer in the range of about 4 to about 48 and the polyoxyethylene groups constitute about 10 to about percent by weight of said copolymer, the average molecular weight of the polyoxypropylene in said copolymer being in the range of about 800 to about 3,000.

References Cited UNITED STATES PATENTS 3,294,537 12/1966 Milton 96-114 3,294,540 12/1966 Goffe 96-114 3,052,544 9/1962 Dersch 96-114 2,995,444 8/1961 Dersch 96l 14 RONALD H. SMITH, Primary Examiner US. Cl. X.R. 961l4 Disclaimer 3,516,830.Th0mas E. Whiteley, Rochester, N.Y. PHOTOGRAPHIC SIL- VER HALIDE EMULSIONS AND ELEMENTS. Patent dated June 23, 1970. Disclaimer filed July 20, 1973, by the assignee, Eastman Kodak Company. Hereby enters this disclaimer to all claims of said patent.

[Oficial Gazette December 11, 1973.] 

